U.S. patent application number 16/094627 was filed with the patent office on 2019-04-11 for coated films and packages formed from same.
The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to Mechelle Ann Churchfield, Larry Jopko, Anne M. Kelly-Rowley, Paul J. Popa, Cristina Serrat, Nicole L. Wagner.
Application Number | 20190105884 16/094627 |
Document ID | / |
Family ID | 59091564 |
Filed Date | 2019-04-11 |
United States Patent
Application |
20190105884 |
Kind Code |
A1 |
Kelly-Rowley; Anne M. ; et
al. |
April 11, 2019 |
COATED FILMS AND PACKAGES FORMED FROM SAME
Abstract
The present invention provides coated films and packages formed
from such films. In one aspect, a coated film comprises (a) a film
comprising (i) a first layer comprising from 70 to 100 percent by
weight of a polyethylene having a density 0.930 g/cm.sup.3 or less
and a peak melting point of less than 126.degree. C.; (ii) a second
layer comprising from 60 to 100 percent by weight polyethylene
having a density of 0.905 to 0.970 g/cm.sup.3 and a peak melting
point in the range of 100.degree. C. to 135.degree. C.; and (iii)
at least one inner layer between the first layer and the second
layer comprising from 40 to 100 percent by weight of a polyethylene
having a density from 0.930 to 0.970 g/cm.sup.3 and a peak melting
point in the range of 120.degree. C. to 135.degree. C., wherein the
polyethylene is a medium density polyethylene or a high density
polyethylene; and (b) a coating on an outer surface of the second
layer of the film comprising a crosslinked polyurethane, wherein
the coating is substantially free of isocyanate groups. In some
embodiments, the coated film is thermally resistant when subjected
to a W-fold test at a temperature of at least 230.degree. F.,
and/or has a gloss of at least 70 units at 60.degree..
Inventors: |
Kelly-Rowley; Anne M.;
(Midland, MI) ; Churchfield; Mechelle Ann;
(Midland, MI) ; Wagner; Nicole L.; (Midland,
MI) ; Popa; Paul J.; (Auburn, MI) ; Jopko;
Larry; (Lake Jackson, TX) ; Serrat; Cristina;
(Sugar Land, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Family ID: |
59091564 |
Appl. No.: |
16/094627 |
Filed: |
May 25, 2017 |
PCT Filed: |
May 25, 2017 |
PCT NO: |
PCT/US2017/034525 |
371 Date: |
October 18, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62343428 |
May 31, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 27/325 20130101;
C08J 2475/04 20130101; C08J 2323/08 20130101; B32B 2307/72
20130101; B32B 2255/26 20130101; B32B 2250/24 20130101; B32B 27/20
20130101; C08J 7/0427 20200101; B32B 2307/7248 20130101; B32B 27/34
20130101; B32B 2307/3065 20130101; B32B 2307/71 20130101; B32B
27/08 20130101; B32B 2307/21 20130101; B32B 27/18 20130101; B32B
2307/7145 20130101; B32B 2264/10 20130101; B32B 7/12 20130101; B32B
27/306 20130101; B32B 2439/06 20130101; B32B 27/32 20130101; B32B
2264/102 20130101; B32B 2255/10 20130101; B32B 27/327 20130101;
B32B 2264/104 20130101; B32B 2307/746 20130101 |
International
Class: |
B32B 27/32 20060101
B32B027/32; C08J 7/04 20060101 C08J007/04 |
Claims
1. A coated film comprising: (a) a film comprising: (i) a first
layer comprising from 70 to 100 percent by weight of a polyethylene
having a density of 0.930 g/cm.sup.3 or less and a peak melting
point of less than 126.degree. C.; (ii) a second layer comprising
from 60 to 100 percent by weight polyethylene having a density of
0.905 to 0.970 g/cm.sup.3 and a peak melting point in the range of
100.degree. C. to 135.degree. C.; and (iii) at least one inner
layer between the first layer and the second layer comprising from
40 to 100 percent by weight of a polyethylene having a density from
0.930 to 0.970 g/cm.sup.3 and a peak melting point in the range of
120.degree. C. to 135.degree. C., wherein the polyethylene is a
medium density polyethylene or a high density polyethylene; and (b)
a coating on an outer surface of the second layer of the film
comprising a crosslinked polyurethane, wherein the coating is
substantially free of isocyanate groups.
2. The coated film of claim 1, wherein the coated film is thermally
resistant when subjected to a W-fold test at a temperature of at
least 230.degree. F.
3. The coated film of claim 1, wherein the coated film has a gloss
of at least 70 units at 60.degree..
4. The coated film according to claim 1, wherein the film is a
blown film.
5. The coated film according to claim 1, wherein the amount of
coating on the outer surface of the first layer of the film is 1 to
7 g/m.sup.2.
6. The coated film according to claim 1, wherein the coated film
has a kinetic coefficient of friction of 0.10 to 1.5 on the coated
surface.
7. The coated film according to claim 1, wherein the polyurethane
is formed from: (a) a polycarbamate having an average of 2.5 or
more carbamate functional groups; and (b) a polyaldehyde, wherein
the polyaldehyde is a dialdehyde, a trialdehyde, or an acetal or
hemiacetal thereof, and wherein the polyaldehyde comprises 2 to 20
carbon atoms.
8. The coated film according to claim 1, wherein the coating
further comprises at least one of oil and wax.
9. The coated film according to claim 1, wherein the film comprises
one or more lower density inner layers between the first layer and
the second layer comprising from 50 to 100 percent by weight
polyethylene having a density of 0.92 g/cm.sup.3 or less and a peak
melting point in the range of 120.degree. C. to 135.degree. C.
10. The coated film according to claim 1, wherein one or more of
the layers further comprise polypropylene, a cyclic olefin
copolymer, or mixtures thereof in an amount of 50% by weight or
less, preferably less than 30% by weight.
11. The coated film according to claim 1, further comprising a
barrier layer.
12. A coated film comprising: (a) a monolayer film comprising from
70 to 100 percent by weight polyethylene having a density less than
0.930 g/cm.sup.3 and a melt index (I.sub.2) of less than 2.0 g/10
minutes, and a peak melting point of less than 126.degree. C.; and
(b) a coating on an outer surface of the film comprising a
crosslinked polyurethane, wherein the coating is substantially free
of isocyanate groups.
13. The coated film of claim 12, wherein the coated film is
thermally resistant when subjected to a W-fold test at a
temperature of at least 230.degree. F.
14. An article comprising the coated film according to claim 1.
15. The article according to claim 14, wherein the coated film has
a thickness of 20 to 200 microns.
Description
FIELD
[0001] The present invention relates to coated films that can be
used in packages. Such coated films can be particularly useful in
food packages such as stand-up pouches.
INTRODUCTION
[0002] For years, many types of flexible and semi-rigid packaging
created to protect food, liquids, personal care items, and other
consumer products have been manufactured with a structure that
typically combines polyester and/or polypropylene layer(s) with
polyethylene films using a reactive polyurethane adhesive to make a
laminate of the various layers. Such film structures combine the
gloss, stiffness, thermal resistance, and oxygen barrier properties
of polyester and/or polypropylene layers with the water vapor
barrier, mechanical, and sealing properties of polyethylene layers.
In addition, some packages include metal foil layers, paperboard
layers, and other layers. Of course, the barrier properties
(resistance (or lack of resistance) to oxygen and water vapor
transmission) can be selected based on the type of product to be
packaged.
[0003] While such packages combine a number of properties, one of
the primary challenges of such packages is the many conversion and
fabrication steps that can be required to manufacture the package.
Another challenge with such packages is the disposal of such
packages. With such packages being made up of mixed plastics and/or
metal foils and/or paperboard, the packages are usually discarded
as waste due to the incompatibility of these materials.
[0004] It would thus be desirable to have films for use in packages
that are substantially made from a single material (e.g.,
polyethylene), that is, made with one or more layers formed from
the same material (e.g., polyethylene), while minimizing the
presence of other materials except as needed to provide a
functionality that the primary material used is not able to
provide.
SUMMARY
[0005] The present invention provides coated films that
advantageously combine polyethylene-based films (including
monolayer and multi-layer films, with and without lamination to
polyethylene films) with a polyurethane coating that advantageously
provide desirable properties to packages for an improved
compatibility/recyclability profile. In some embodiments, the
present invention provides coated films for packages that have
sealing temperature ranges and gloss that are comparable to
polyester or polypropylene-based films but that can be produced in
simplified manufacturing processes. For example, in some
embodiments, the polyurethane coating can be applied to an outer
surface of a polyethylene-based film in-line (e.g., following
extrusion) to provide the coated films. In some embodiments, the
polyurethane coating is substantially free of isocyanate groups. In
some embodiments, the present invention advantageously simplifies
film production processes for packaging and minimizes the use of
incompatible materials that cause difficulties in recycling.
[0006] In one aspect, the present invention provides a coated film
that comprises (a) a film comprising (i) a first layer comprising
from 70 to 100 percent by weight of a polyethylene having a density
of 0.930 g/cm.sup.3 or less and a peak melting point of less than
126.degree. C.; (ii) a second layer comprising from 60 to 100
percent by weight polyethylene having a density of 0.905 to 0.970
g/cm.sup.3 and a peak melting point in the range of 100.degree. C.
to 135.degree. C.; and (iii) at least one inner layer between the
first layer and the second layer comprising from 40 to 100 percent
by weight of a polyethylene having a density from 0.930 to 0.970
g/cm.sup.3 and a peak melting point in the range of 120.degree. C.
to 135.degree. C., wherein the polyethylene is a medium density
polyethylene or a high density polyethylene; and (b) a coating on
an outer surface of the second layer of the film comprising a
crosslinked polyurethane, wherein the coating is substantially free
of isocyanate groups. In some embodiments, the coated film is
thermally resistant when subjected to a W-fold test at a
temperature of at least 230.degree. F., and/or has a gloss of at
least 70 units at 60.degree.. In some embodiments, the first layer
is a sealing layer.
[0007] In another aspect, the present invention provides a coated
film that comprises (a) a monolayer film comprising from 70 to 100
percent by weight polyethylene having a density of 0.930 g/cm.sup.3
or less and a melt index (I.sub.2) of less than 2.0 g/10 minutes,
and a peak melting point of less than 126.degree. C.; and (b) a
coating on an outer surface of the film comprising crosslinked
polyurethane, wherein the coating is substantially free of
isocyanate groups. In some embodiments, the coated film is
thermally resistant when subjected to a W-fold test at a
temperature of at least 230.degree. F., and/or has a gloss of at
least 70 units at 60.degree.. Such temperature ranges can
facilitate the use of such coated films in form fill and seal
packaging processes with minimal detriment on productivity.
[0008] Embodiments of the present invention also provide articles
(e.g., pillow pouches, stand-up pouches, etc.) formed from the
coated films disclosed herein.
[0009] These and other embodiments are described in more detail in
the Detailed Description.
DETAILED DESCRIPTION
[0010] Unless specified otherwise herein, percentages are weight
percentages (wt %) and temperatures are in .degree. C.
[0011] The term "composition," as used herein, includes material(s)
which comprise the composition, as well as reaction products and
decomposition products formed from the materials of the
composition.
[0012] The term "comprising," and derivatives thereof, is not
intended to exclude the presence of any additional component, step
or procedure, whether or not the same is disclosed herein. In order
to avoid any doubt, all compositions claimed herein through use of
the term "comprising" may include any additional additive,
adjuvant, or compound, whether polymeric or otherwise, unless
stated to the contrary. In contrast, the term, "consisting
essentially of" excludes from the scope of any succeeding
recitation any other component, step or procedure, excepting those
that are not essential to operability. The term "consisting of"
excludes any component, step or procedure not specifically
delineated or listed.
[0013] The term "polymer," as used herein, refers to a polymeric
compound prepared by polymerizing monomers, whether of the same or
a different type. The generic term polymer thus embraces the term
homopolymer (employed to refer to polymers prepared from only one
type of monomer, with the understanding that trace amounts of
impurities can be incorporated into the polymer structure), and the
term interpolymer as defined hereinafter. Trace amounts of
impurities may be incorporated into and/or within the polymer.
[0014] The term "interpolymer," as used herein, refers to a polymer
prepared by the polymerization of at least two different types of
monomers. The generic term interpolymer thus includes copolymers
(employed to refer to polymers prepared from two different types of
monomers), and polymers prepared from more than two different types
of monomers. The term "polymer", as used herein, refers to a
polymeric compound prepared by polymerizing monomers, whether of
the same or a different type. The generic term polymer thus
embraces the term "homopolymer", usually employed to refer to
polymers prepared from only one type of monomer as well as
"copolymer" which refers to polymers prepared from two or more
different monomers.
[0015] "Polyethylene" shall mean polymers comprising greater than
50% by weight of units which have been derived from ethylene
monomer. This includes polyethylene homopolymers or copolymers
(meaning units derived from two or more comonomers). Common forms
of polyethylene known in the art include Low Density Polyethylene
(LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density
Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single
site catalyzed Linear Low Density Polyethylene, including both
linear and substantially linear low density resins (m-LLDPE);
Medium Density Polyethylene (MDPE); and High Density Polyethylene
(HDPE). These polyethylene materials are generally known in the
art; however the following descriptions may be helpful in
understanding the differences between some of these different
polyethylene resins.
[0016] The term "LDPE" may also be referred to as "high pressure
ethylene polymer" or "highly branched polyethylene" and is defined
to mean that the polymer is partly or entirely homopolymerized or
copolymerized in autoclave or tubular reactors at pressures above
14,500 psi (100 MPa) with the use of free-radical initiators, such
as peroxides (see for example U.S. Pat. No. 4,599,392, which is
hereby incorporated by reference). LDPE resins typically have a
density in the range of 0.916 to 0.940 g/cm.sup.3.
[0017] The term "LLDPE", includes resins made using the traditional
Ziegler-Natta catalyst systems as well as single-site catalysts
such as bis-metallocenes (sometimes referred to as "m-LLDPE"),
post-metallocene catalysts, and constrained geometry catalysts, and
includes linear, substantially linear or heterogeneous polyethylene
copolymers or homopolymers. LLDPEs contain less long chain
branching than LDPEs and includes the substantially linear ethylene
polymers which are further defined in U.S. Pat. Nos. 5,272,236,
5,278,272, 5,582,923 and 5,733,155; the homogeneously branched
linear ethylene polymer compositions such as those in U.S. Pat. No.
3,645,992; the heterogeneously branched ethylene polymers such as
those prepared according to the process disclosed in U.S. Pat. No.
4,076,698; and/or blends thereof (such as those disclosed in U.S.
Pat. Nos. 3,914,342 or 5,854,045). The LLDPEs can be made via
gas-phase, solution-phase or slurry polymerization or any
combination thereof, using any type of reactor or reactor
configuration known in the art, with gas and slurry phase reactors
being most preferred.
[0018] The term "MDPE" refers to polyethylenes having densities
from 0.926 to 0.940 g/cm.sup.3. "MDPE" is typically made using
chromium or Ziegler-Natta catalysts or using metallocene,
constrained geometry, or single site catalysts, and typically have
a molecular weight distribution ("MWD") greater than 2.5.
[0019] The term "HDPE" refers to polyethylenes having densities
greater than about 0.940 g/cm.sup.3, which are generally prepared
with Ziegler-Natta catalysts, chrome catalysts, post-metallocene
catalysts, or constrained geometry catalysts.
[0020] "Multimodal" means resin compositions which can be
characterized by having at least two distinct peaks in a GPC
chromatogram showing the molecular weight distribution. Multimodal
includes resins having two peaks as well as resins having more than
two peaks.
[0021] As used herein, the term "polyaldehyde" means a molecule
containing two or more aldehyde groups or their hydrates, or their
acetals or hemiacetals, wherein the molecule is capable of
performing as described herein and is capable of reacting with the
polycarbamate during the invention curing step so as to form the
invention crosslinked polyurethane. The aldehyde group can be
written herein as --C(.dbd.O)H or --CHO. The term "polyaldehyde" is
not used herein to mean a polymeric substance made by
self-polymerizing an aldehyde monomer.
[0022] Unless otherwise noted herein, the term "carbamate group"
means a radical structure of formula
##STR00001##
[0023] As used herein, the term "polycarbamate" means a molecule
containing two or more carbamate groups (H.sub.2NC(O)O--), wherein
the molecule is capable of reacting with the polyaldehyde during
the invention curing step so as to form the invention crosslinked
polyurethane.
[0024] As used herein, the term "substantially free of isocyanate
groups" or "substantially isocyanate-free" groups means having less
than 5 mole percent (mol %) of --N.dbd.C.dbd.O groups (i.e.,
isocyanate groups) based on total moles of carbamate groups plus
isocyanate groups in the composition, preferably, less than 3 mol
%, or, more preferably, less than 1 mol %, and, still more
preferably, less than 0.1 mol %.
[0025] As used herein, the term "crosslinked polyurethane" means a
polymeric substance comprising two adjacent molecular backbones,
each of which independently contains a plurality of repeat units,
each repeat unit independently comprising a connecting carbamate
diradical, or any two adjacent repeat units together comprising a
connecting carbamate diradical, or a combination thereof; wherein
the adjacent molecular backbones are covalently bonded together via
at least one covalent bond of the connecting carbamate diradical,
thereby covalently bonding the adjacent molecular backbones
together so as to form a single crosslinked polyurethane molecule.
The connecting carbamate diradical is described later.
[0026] As used herein, the term "carbamate diradical" means a "
##STR00002##
" group.
[0027] As used herein, "
##STR00003##
" (or an end "-" taken in context) indicates a radical. Each of the
covalently bonded adjacent molecular backbones independently is
linear or branched and independently contains zero, one, or more
cyclic groups, including aromatic groups. Each molecular backbone
can be covalently bonded to one or more other molecular
backbones.
[0028] As used herein, the term "curing" means subjecting to
conditions effective for chemically transforming or chemically
transforming under such conditions.
[0029] As used herein, the term "curing temperature" means a degree
of hotness or coldness effective for chemically transforming the
invention ambient temperature curable composition to the invention
crosslinked polyurethane. As used herein, the term "crosslinked
polyurethane" means a polymeric substance comprising two adjacent
molecular backbones, each of which independently contains a
plurality of repeat units, each repeat unit independently
comprising a connecting carbamate diradical, or any two adjacent
repeat units together comprising a connecting carbamate diradical,
or a combination thereof;
[0030] wherein the adjacent molecular backbones are covalently
bonded together via at least one covalent bond of the connecting
carbamate diradical, thereby covalently bonding the adjacent
molecular backbones together so as to form a single crosslinked
polyurethane molecule. The connecting carbamate diradical is
described later.
[0031] As used herein, the term "carbamate diradical" means a " "
group.
[0032] As used herein, " " (or an end "-" taken in context)
indicates a radical. Each of the covalently bonded adjacent
molecular backbones independently is linear or branched and
independently contains zero, one, or more cyclic groups, including
aromatic groups. Each molecular backbone can be covalently bonded
to one or more other molecular backbones.
[0033] As used herein, the term "curing" means subjecting to
conditions effective for chemically transforming or chemically
transforming under such conditions.
[0034] As used herein, the term "curing temperature" means a degree
of hotness or coldness effective for chemically transforming the
invention ambient temperature curable composition to the invention
crosslinked polyurethane.
[0035] Unless otherwise indicated herein, the following analytical
methods are used in the describing aspects of the present
invention:
[0036] Melt index: Melt indices I.sub.2 (or I2) and I.sub.10 (or
I10) are measured in accordance to ASTM D-1238 at 190.degree. C.
and at 2.16 kg and 10 kg load, respectively. Their values are
reported in g/10 min.
[0037] Density: Samples for density measurement are prepared
according to ASTM D4703. Measurements are made, according to ASTM
D792, Method B, within one hour of sample pressing.
[0038] Peak melting point is determined by Differential Scanning
calorimeter (DSC) where the film is conditioned at 230.degree. C.
for 3 minutes prior to cooling at a rate of 10.degree. C. per
minute to a temperature of 40.degree. C. After the film is kept at
-40.degree. C. for 3 minutes, the film is heated to 200.degree. C.
at a rate of 10.degree. C. per minute.
[0039] The term molecular weight distribution or "MWD" is defined
as the ratio of weight average molecular weight to number average
molecular weight (M.sub.w/M.sub.n). M.sub.w and M.sub.n are
determined according to methods known in the art using conventional
gel permeation chromatography (conventional GPC).
[0040] Gloss is determined according to ASTM D2457.
[0041] Coefficient of Friction is determined according to ASTM
1894.
[0042] Additional properties and test methods are described further
herein.
[0043] In one aspect, the present invention provides a coated film
that comprises (a) a film comprising (i) a first layer comprising
from 70 to 100 percent by weight of a polyethylene having a density
of 0.930 g/cm.sup.3 or less and a peak melting point of less than
126.degree. C.; (ii) a second layer comprising from 60 to 100
percent by weight polyethylene having a density of 0.905 to 0.970
g/cm.sup.3 and a peak melting point in the range of 100.degree. C.
to 135.degree. C.; and (iii) at least one inner layer between the
first layer and the second layer comprising from 40 to 100 percent
by weight of a polyethylene having a density from 0.930 to 0.970
g/cm.sup.3 and a peak melting point in the range of 120.degree. C.
to 135.degree. C., wherein the polyethylene is a medium density
polyethylene or a high density polyethylene; and (b) a coating on
an outer surface of the second layer of the film comprising a
crosslinked polyurethane, wherein the coating is substantially free
of isocyanate groups.
[0044] In another aspect, the present invention provides a coated
film that comprises (a) a film comprising (i) a first layer
comprising from 70 to 100 percent by weight of a polyethylene
having a density of 0.930 g/cm.sup.3 or less and a peak melting
point of less than 126.degree. C.; (ii) a second layer comprising
from 60 to 100 percent by weight polyethylene having a density of
0.905 to 0.970 g/cm.sup.3 and a peak melting point in the range of
100.degree. C. to 135.degree. C.; and (iii) at least one inner
layer between the first layer and the second layer comprising from
40 to 100 percent by weight of a polyethylene having a density from
0.930 to 0.970 g/cm.sup.3 and a peak melting point in the range of
120.degree. C. to 135.degree. C., wherein the polyethylene is a
medium density polyethylene or a high density polyethylene; and (b)
a coating on an outer surface of the second layer of the film
comprising a crosslinked polyurethane, wherein the coating is
substantially free of isocyanate groups, wherein the coated film is
thermally resistant when subjected to a W-fold test at a
temperature of at least 230.degree. F., and/or has a gloss of at
least 70 units at 60.degree..
[0045] In another aspect, the present invention provides a coated
film that comprises (a) a monolayer film comprising from 70 to 100
percent by weight polyethylene having a density of 0.930 g/cm.sup.3
or less and a melt index (I.sub.2) of less than 2.0 g/10 minutes,
and a peak melting point of less than 126.degree. C.; and (b) a
coating on an outer surface of the film comprising a crosslinked
polyurethane, wherein the coating is substantially free of
isocyanate groups. In another aspect, the present invention
provides a coated film that comprises (a) a monolayer film
comprising from 70 to 100 percent by weight polyethylene having a
density of 0.930 g/cm.sup.3 or less and a melt index (I.sub.2) of
less than 2.0 g/10 minutes, and a peak melting point of less than
126.degree. C.; and (b) a coating on an outer surface of the film
comprising a crosslinked polyurethane, wherein the coating is
substantially free of isocyanate groups, wherein the coated film is
thermally resistant when subjected to a W-fold test at a
temperature of at least 230.degree. F., and/or has a gloss of at
least 70 units at 60.degree..
[0046] In some embodiments, the polyurethane is formed from: (a) a
polycarbamate having an average of 2.5 or more carbamate functional
groups; and (b) a polyaldehyde, wherein the polyaldehyde is a
dialdehyde, a trialdehyde, or an acetal or hemiacetal thereof, and
wherein the polyaldehyde comprises 2 to 20 carbon atoms. Additional
details regarding the polyurethane that can be used in the coating
in various embodiments of the present invention are provided
herein. In some embodiments, the coating further comprises at least
one of oil and wax.
[0047] The coated film is a blown film in some embodiments. In
embodiments where the coated film is a multilayer blown film, the
polyethylene in the first layer, the polyethylene in the second
layer, and the polyethylene in at least one additional layer each
have a melt index (I.sub.2) of less than 2.0 g/10 minutes.
[0048] In some embodiments, the coated film is a cast film. In
embodiments where the coated film is a multilayer cast film, the
polyethylene in the first layer, the polyethylene in the second
layer, and the polyethylene in the at least one additional layer
each have a melt index (I.sub.2) of 2.0 g/10 minutes or more. In
some embodiments, one or more of the polyethylene in the first
layer, the polyethylene in the second layer, and the polyethylene
in the at least one additional layer can have a melt index
(I.sub.2) of less than 2.0 g/10 minutes. In some embodiments, one
or more of the polyethylene in the first layer, the polyethylene in
the second layer, and the polyethylene in the at least one
additional layer can have a melt index (I.sub.2) of 0.1-2.0 g/10
minutes, or 0.5-2.0 g/10 minutes.
[0049] The coated film, in some embodiments, has a gloss of at
least 85 units at 60.degree..
[0050] The amount of coating on the outer surface of the film (or
the outer surface of a layer of a multilayer film), in some
embodiments, is 1 to 7 g/m.sup.2.
[0051] In some embodiments, the coated film has a kinetic
coefficient of friction of 0.10 to 1.5 on the coated surface.
[0052] In some embodiments where the film is a multilayer layer
film comprising two or more layers, the film can comprise one or
more lower density inner layers between the first layer and the
second layer comprising from 50 to 100 percent by weight
polyethylene having a density of 0.92 g/cm.sup.3 or less, and a
peak melting point in the range of 90.degree. C. to 120.degree. C.,
preferably 100.degree. C. to 115.degree. C. In some embodiments
where the film is a multilayer layer film comprising two or more
layers, the film can comprise one or more layers comprising
polypropylene, propylene-based copolymers, a cyclic olefin
copolymer, or mixtures thereof. In some embodiments where the film
is a multilayer layer film comprising two or more layers, the film
can further comprise a barrier layer. A barrier layer, in such
embodiments, can comprise, for example, polyamide or ethylene vinyl
alcohol.
[0053] Embodiments of the present invention also provide articles
formed from any of the coated films described herein. In some such
embodiments, the coated film has a thickness of 20 to 200 microns.
Examples of such articles can include flexible packages, like
pillow pouches and stand-up pouches. In some embodiments, coated
films of the present invention can be used in form, fill and seal
processes to make packages or other articles.
[0054] As noted above, in some embodiments, the film is a
multilayer film. In such embodiments, a first layer comprises from
70 to 100 percent by weight of polyethylene having a density of
0.930 g/cm.sup.3 or less. The first layer is a surface layer in
some embodiments. All individual values and subranges from 70 to
100 percent by weight (wt %) are included herein and disclosed
herein; for example the amount of the linear low density
polyethylene can be from a lower limit of 70, 80, or 90 wt % to an
upper limit of 80, 90, or 100 wt %. For example, the amount of the
first linear low density polyethylene can be from 80 to 100 wt %,
or in the alternative, from 70 to 90 wt %, or in the alternative,
from 75 to 95 wt %, or in the alternative from 80 to 100 wt %.
[0055] The polyethylene in the first layer has a density less than
or equal to 0.930 g/cc (cm.sup.3). All individual values and
subranges less than or equal to 0.930 g/cc are included herein and
disclosed herein; for example, the density of the polyethylene can
be from an upper limit of 0.928, 0.925, 0.920 or 0.915 g/cc In some
aspects of the invention, the polyethylene in the first layer has a
density greater than or equal to 0.870 g/cc. All individual values
and subranges between 0.870 and 0.930 are included herein and
disclosed herein.
[0056] The polyethylene having a density of 0.930 g/cm.sup.3 or
less in the first layer has a peak melting point of 126.degree. C.
or less in some embodiments, preferably between 70 and 121.degree.
C., more preferably between 80 and 121.degree. C.
[0057] The melt index of the polyethylene having a density of 0.930
g/cm.sup.3 or less in the first layer can depend on a number of
factors including whether the film is a blown film or a cast film.
In embodiments where the film is a blown film, the polyethylene in
the first layer has an 12 less than or equal to 2.0 g/10 minutes.
All individual values and subranges from -2.0 g/10 minutes are
included herein and disclosed herein. For example, the polyethylene
can have a melt index from an upper limit of 2.0, 1.7, 1.4, 1.1, or
0.9 g/10 minutes. In a particular aspect of the invention, the
polyethylene has an 12 with a lower limit of 0.1 g/10 minutes. All
individual values and subranges from 0. 1 g/10 minutes are included
herein and disclosed herein. For example, the polyethylene in the
first layer can have an I.sub.2 greater than or equal to 0.1, 0.2,
0.3, or 0.4 g/10 minutes.
[0058] In other embodiments, the film can be a cast film. In such
embodiments, the polyethylene having a density of 0.930 g/cm.sup.3
or less in the first layer has an I.sub.2 greater than or equal to
2.0 g/10 minutes. All individual values and subranges above 2.0
g/10 minutes are included herein and disclosed herein. For example,
the polyethylene can have a melt index from a lower limit of 2.0,
3.0, 4.0, 5.0, 6.0, or 10 g/10 minutes. In some embodiments, the
polyethylene for a cast film application can have an upper melt
index limit of 15 g/10 minutes. In some embodiments, depending on
the other components in the first layer or other layers, the
polyethylene in the first layer for a cast film application can
have an upper limit of 12 of less than 2.0 g/10 minutes. In some
embodiments, the polyethylene in the first layer for a cast film
application can have a melt index (I.sub.2) of 0.1-2.0 g/10
minutes, or 0.5-2.0 g/10 minutes. All individual values and
subranges from 0.1 to 2.0 g/10 minutes are included herein and
disclosed herein.
[0059] Examples of polyethylenes having a density of 0.930
g/cm.sup.3 or less that can be used in the first layer include
linear low density polyethylenes, polyolefin plastomers, ultra low
density polyethylenes, and enhanced polyethylenes. Such
polyethylenes include those commercially available from The Dow
Chemical Company under the names AFFINITY.TM., ELITE.TM. AT, and
ATTANE.TM. including, for example, AFFINITY.TM. PL 1146G polyolefin
plastomer, AFFINITY.TM. PL 1888 polyolefin plastomer, ELITE.TM. AT
6401 enhanced polyethylene, ELITE.TM. 5401G enhanced polyethylene,
and ATTANE.TM. 4203 ultra low density polyethylene.
[0060] In embodiments where the first layer comprises <100% of
the polyethylene having a density of 0.930 g/cm.sup.3 or less, the
first layer further comprises one or more additional polyethylene
resins such as, for example, one or more low density polyethylenes
having a melt index from 0.1 to 5 g/10 minutes, one or more linear
low density polyethylenes having a density of 0.930 g/cc or more
and a melt index from 0.1 to 5 g/10 minutes.
[0061] In embodiments wherein the film comprises a multilayer film,
a second layer comprises from 60 to 100 percent by weight of a
polyethylene. The second layer is another surface layer in some
embodiments. All individual values and subranges from 60 to 100
percent by weight (wt %) are included herein and disclosed herein;
for example the amount of the polyethylene can be from a lower
limit of 60, 70, 80, or 90 wt % to an upper limit of 70, 80, 90, or
100 wt %. For example, the amount of the polyethylene can be from
70 to 100 wt %, or in the alternative, from 60 to 90 wt %, or in
the alternative, from 65 to 95 wt %, or in the alternative from 70
to 100 wt %.
[0062] The polyethylene in the second layer has a density of 0.905
to 0.970 g/cc (cm.sup.3). All individual values and subranges from
0.910 to 0.970 g/cc are included herein and disclosed herein; for
example, the density of the polyethylene can be from a lower limit
of 0.905, 0.910, 0.920, 0.930, 0.940, or 0.950 g/cc to an upper
limit of 0.930, 0.940, 0.950, 0.960, 0.970 g/cc. In some
embodiments, the polyethylene has a density from 0.910 to 0.970
g/cc, preferably between 0.920 to 0.960 g/cc, more preferably
between 0.940 to 0.960 g/cc.
[0063] The polyethylene in the second layer has a peak melting
point of 100.degree. C. to 135.degree. C. in some embodiments,
preferably between 121 and 132.degree. C., more preferably between
126 and 132.degree. C.
[0064] The melt index of the polyethylene in the second layer can
depend on a number of factors including whether the film is a blown
film or a cast film. In embodiments where the film is a blown film,
the polyethylene has an 12 less than or equal to 2.0 g/10 minutes.
All individual values and subranges from 2.0 g/10 minutes are
included herein and disclosed herein. For example, the polyethylene
can have a density from an upper limit of 2.0, 1.7, 1.4, 1.1, or
0.9 g/10 minutes. In a particular aspect of the invention, the
polyethylene has an I.sub.2 with a lower limit of 0.1 g/10 minutes.
All individual values and subranges from 0.1 g/10 minutes are
included herein and disclosed herein. For example, the polyethylene
can have an I.sub.2 greater than or equal to 0.1, 0.2, 0.3, or 0.5
g/10 minutes.
[0065] In other embodiments, the film can be a cast film. In such
embodiments, the polyethylene in the second layer has an I.sub.2
greater than or equal to 2.0 g/10 minutes. All individual values
and subranges above 2.0 g/10 minutes are included herein and
disclosed herein. For example, the first linear low density
polyethylene can have a melt index from a lower limit of 2.0, 3.0,
4.0, 5.0, 6.0, or 10 g/10 minutes. In some embodiments, the
polyethylene in the second layer for a cast film application can
have an 12 of up to 15 g/10 minutes. In some embodiments, depending
on the other components in the second layer or other layers, the
polyethylene in the second layer for a cast film application can
have an upper limit of 12 of less than 2.0 g/10 minutes. In some
embodiments, the polyethylene in the second layer for a cast film
application can have a melt index (I.sub.2) of 0.1-2.0 g/10
minutes, or 0.5-2.0 g/10 minutes. All individual values and
subranges from 0.1 to 2.0 g/10 minutes are included herein and
disclosed herein.
[0066] Examples of polyethylenes that can be used in the second
layer include those commercially available from The Dow Chemical
Company under the names DOWLEX.TM. and ELITE.TM., and ATTANE.TM.,
such as DOWLEX.TM. 2045G, DOWLEX.TM. 2038.68, ELITE.TM. 5111G,
ELITE.TM. 5400G, ELITE.TM. 5960G, and ATTANE.TM. 4203.
[0067] In embodiments where the second layer comprises <100% of
the polyethylene described above, the second layer further
comprises one or more additional polyethylene resins such as, for
example, one or more low density polyethylenes having a melt index
from 0.1 to 5 g/10 minutes, one or more additional linear low
density polyethylenes having a density of 0.930 g/cc or less and a
melt index from 0.1 to 5 g/10 minutes.
[0068] In embodiments wherein the film is a multilayer film having
first and second layers as described above, the film can further
comprise one or more inner layers between the first layer and the
second layer. In such embodiments, at least one of the inner layers
can comprise from 40 to 100 percent by weight of a high density
polyethylene (HDPE) and/or medium density polyethylene (MDPE). All
individual values and subranges from 40 to 100 percent by weight
(wt %) are included herein and disclosed herein; for example the
amount of the high density polyethylene can be from a lower limit
of 40, 50, 60, 70, 80, or 90 wt % to an upper limit of 50, 60, 70,
80, 90, or 100 wt %. For example, the amount of the high density
polyethylene can be from 50 to 100 wt %, or in the alternative,
from 60 to 90 wt %, or in the alternative, from 65 to 95 wt %, or
in the alternative from 70 to 100 wt %.
[0069] When an inner layer includes a medium density polyethylene,
the medium density polyethylene has a density of 0.930 g/cc
(cm.sup.3) to 0.940 g/cc. All individual values and subranges from
0.930 to 0.940 g/cc are included herein and disclosed herein; for
example, the density of the polyethylene can be from a lower limit
of 0.930, 0.935, or 0.937 g/cc to an upper limit of 0.935, 0.937,
or 0.940 g/cc.
[0070] When an inner layer includes a high density polyethylene,
the high density polyethylene has a density of 0.940 g/cc
(cm.sup.3) to 0.970 g/cc. All individual values and subranges from
0.940 to 0.970 g/cc are included herein and disclosed herein; for
example, the density of the polyethylene can be from a lower limit
of 0.940, 0.945, 0.950, or 0.960 g/cc to an upper limit of 0.950,
0.960, or 0.970 g/cc. In some embodiments, the high density
polyethylene has a density of 0.940 g/cc or more.
[0071] The medium density polyethylene and/or high density
polyethylene has a peak melting point of 126.degree. C. to
135.degree. C. in some embodiments, preferably between 126 and
132.degree. C., more preferably between 127 and 132.degree. C.
[0072] The melt index of the medium density and/or high density
polyethylene in the at least one inner layer can depend on a number
of factors including whether the film is a blown film or a cast
film. In embodiments where the film is a blown film, the medium
and/or high density polyethylene has an I.sub.2 less than or equal
to 2.0 g/10 minutes. All individual values and subranges from 2.0
g/10 minutes are included herein and disclosed herein. For example,
the medium and/or high density polyethylene can have a density from
an upper limit of 2.0, 1.7, 1.4, 1.1, or 0.9 g/10 minutes. In a
particular aspect of the invention, the medium and/or high density
polyethylene has an 12 with a lower limit of 0.1 g/10 minutes. All
individual values and subranges from 0.1 g/10 minutes are included
herein and disclosed herein. For example, the medium and/or high
density polyethylene can have an I.sub.2 greater than or equal to
0.1, 0.2, 0.3, or 0.4 g/10 minutes.
[0073] In other embodiments, the film can be a cast film. In such
embodiments, the medium and/or high density polyethylene has an
I.sub.2 greater than or equal to 2.0 g/10 minutes. All individual
values and subranges above 2.0 g/10 minutes are included herein and
disclosed herein. For example, the medium and/or high density
polyethylene in the at least one inner layer can have a melt index
from a lower limit of 2.0, 3.0, 4.0, 5.0, 6.0, or 10 g/10 minutes.
In some embodiments, the medium and/or high density polyethylene in
the at least one inner layer for a cast film application can have
an 12 of up to 15 g/10 minutes. In some embodiments, depending on
the other components in the inner layer(s) or other layers, the
medium and/or high density polyethylene in the at least one inner
layer for a cast film application can have an upper limit of 12 of
less than 2.0 g/10 minutes. In some embodiments, the medium and/or
high density polyethylene in the at least one inner layer for a
cast film application can have a melt index (I.sub.2) of 0.1-2.0
g/10 minutes, or 0.5-2.0 g/10 minutes. All individual values and
subranges from 0.1 to 2.0 g/10 minutes are included herein and
disclosed herein.
[0074] Examples of medium and high density polyethylenes that can
be used in at least one inner layer include enhanced polyethylenes
commercially available from The Dow Chemical Company under the
names ELITE.TM., such as, ELITE.TM. 5940G and ELITE.TM. 5960G.
[0075] In embodiments where an inner layer comprises <100% of
the polyethylene described above, the inner layer further comprises
one or more additional polyethylene resins such as, for example,
one or more low density polyethylenes having a melt index from 0.1
to 5 g/10 minutes, one or more linear low density polyethylenes
having a density of 0.930 g/cc or less and a melt index from 0.1 to
5 g/10 minutes.
[0076] In addition to an inner layer comprising 40 to 100 percent
by weight of a medium and high density polyethylene, in some
embodiments, the film can comprise one or more additional inner
layers comprising other polyethylenes or combinations of
polyethylenes, such as one or more low density polyethylenes, one
or more linear low density polyethylenes, or combinations thereof.
For example, in one embodiment, the film comprises at least one
additional inner layer wherein the additional inner layer comprises
50 to 100 weight percent of a polyethylene having a density of
0.920 g/cc (cm.sup.3) or less. All individual values and subranges
for a density of polyethylene from 0.920 g/cc are included herein
and disclosed herein; for example, the density of the polyethylene
can be to an upper limit of 0.900, 0.905, 0.910, 0915, or 0.920
g/cc. Such inner layers can be provided, for example, to enhance
the strength of the film.
[0077] The melt index of the polyethylene in the at least one
additional inner layer can depend on a number of factors including
whether the film is a blown film or a cast film. In embodiments
where the film is a blown film, the polyethylene in the at least
one additional layer has an I.sub.2 less than or equal to 2.0 g/10
minutes. All individual values and subranges from 2.0 g/10 minutes
are included herein and disclosed herein. For example, the
polyethylene can have a density from an upper limit of 2.0, 1.7,
1.4, 1.1, or 0.9 g/10 minutes. In a particular aspect of the
invention, the polyethylene has an I.sub.2 with a lower limit of
0.01 g/10 minutes. All individual values and subranges from 0.1
g/10 minutes are included herein and disclosed herein. For example,
the polyethylene can have an I.sub.2 greater than or equal to 0.1,
0.2, 0.3, or 0.4 g/10 minutes.
[0078] In other embodiments, the film can be a cast film. In such
embodiments, the polyethylene in the at least one additional inner
layer has an I.sub.2 greater than or equal to 2.0 g/10 minutes. All
individual values and subranges above 2.0 g/10 minutes are included
herein and disclosed herein. For example, the polyethylene can have
a melt index from a lower limit of 2.0, 3.0, 4.0, 5.0, 6.0, or 10
g/10 minutes. In some embodiments, the polyethylene in the at least
one additional inner layer for a cast film application can have an
I.sub.2 of up to 15 g/10 minutes. In some embodiments, depending on
the other components in the inner layer(s) or other layers, the
polyethylene in the at least one additional inner layer for a cast
film application can have an upper limit of I.sub.2 of less than
2.0 g/10 minutes. In some embodiments, the polyethylene in the at
least one additional inner layer for a cast film application can
have a melt index (I.sub.2) of 0.1-2.0 g/10 minutes, or 0.5-2.0
g/10 minutes. All individual values and subranges from 0.1 to 2.0
g/10 minutes are included herein and disclosed herein.
[0079] Examples of polyethylenes having a density of 0.920 g/cc or
less that can be used in the at least one additional inner layer
include those commercially available from The Dow Chemical Company
under the names DOWLEX.TM., ELITE.TM., and ATTANE.TM., such as
DOWLEX.TM. 2045G, ELITE.TM. 5401G, and ATTANE.TM. 4203G.
[0080] In any of the above layers (but preferably in the inner
layers) of a multilayer film, other polyolefin resins can be
included in addition to the polyethylene for a variety of reasons.
For example, a layer in a multilayer film can comprise other
polyolefin resins, such as polypropylene and/or cyclic olefin
copolymers (e.g., cyclic olefin copolymers commercially available
from TOPAS Advanced Polymers such as TOPAS 6013), to provide
increased stiffness without significant harm to the compatibility
among materials and potential recyclability. In such embodiments,
the additional polyolefin resins can be provided in amounts less
than 50 weight percent.
[0081] In some embodiments, a multilayer film that can be used in
coated films of the present invention can comprise 3 or more
layers. A multilayer film that can be used in coated films of the
present invention can comprise up to 7 layers in some embodiments.
The number of layers in the film can depend on a number of factors
including, for example, the desired thickness of the multilayer
film, the desired properties of the multilayer film, the intended
use of the multilayer film, and other factors.
[0082] In some embodiments, one or more layers in multilayer film
can comprise one or more additives. Additives can include, but are
not limited to, antistatic agents, color enhancers, dyes,
lubricants, fillers (for example, TiO2 or CaCO3), opacifiers,
nucleating agents, partitioning agents, processing aids, pigments,
primary anti-oxidants, secondary anti-oxidants, UV stabilizers,
anti-blocks, slip agents, tackifiers, fire retardants,
anti-microbial agents, odor reducer agents, anti-fungal agents, and
combinations thereof, depending on the requirements of a particular
application.
[0083] In some embodiments, depending on the desired use or
requirements of the film, the film can comprise other layers such
as barrier layers. For example, for some uses, it may be desirable
for the film to provide a barrier to moisture, light, aroma/odor,
and/or oxygen transmission. Such barrier layers can include, for
example, polyamide films, ethylene vinyl alcohol films, layers
formed from or incorporating cyclic olefin copolymers, layers
incorporating clays, talc, mica, or similar materials, and other
layers as known to those of skill in the art. In such embodiments,
one or more tie layers may be included in the film to adhere the
barrier layer(s) to the polyethylene-based layer(s).
[0084] In some embodiments, the polyurethane coating may have
barrier properties.
[0085] In some embodiments, a film to be coated with the
polyurethane coating comprises a monolayer film. In such
embodiments, the monolayer film can comprise from 70 to 100 percent
by weight polyethylene having a density less than 0.930 g/cm.sup.3
and a melt index (12) of less than 2.0 g/10 minutes, and a peak
melting point of less than 126.degree. C. All individual values and
subranges from 70 to 100 percent by weight (wt %) are included
herein and disclosed herein; for example the amount of the
polyethylene can be from a lower limit of 70, 80, or 90 wt % to an
upper limit of 80, 90, or 100 wt %. For example, the amount of the
polyethylene can be from 80 to 100 wt %, or in the alternative,
from 70 to 90 wt %, or in the alternative, from 75 to 95 wt %, or
in the alternative from 80 to 100 wt %.
[0086] The polyethylene used in the monolayer has a density less
than or equal to 0.930 g/cc (cm.sup.3). All individual values and
subranges less than or equal to 0.930 g/cc are included herein and
disclosed herein; for example, the density of the polyethylene can
be from an upper limit of 0.928, 0.925, 0.920 or 0.915 g/cc. In
some aspects of the invention, the polyethylene has a density
greater than or equal to 0.870 g/cc. All individual values and
subranges between 0.870 and 0.930 g/cc are included herein and
disclosed herein.
[0087] The polyethylene used in the monolayer has a peak melting
point of 126.degree. C. or less in some embodiments, preferably
between 70 and 121.degree. C., more preferably between 80 and
121.degree. C.
[0088] The melt index of the polyethylene used in the monolayer
(I.sub.2) is less than or equal to 2.0 g/10 minutes in some
embodiments. All individual values and subranges from 2.0 g/10
minutes are included herein and disclosed herein. For example, the
polyethylene can have a density from an upper limit of 2.0, 1.7,
1.4, 1.1, or 0.9 g/10 minutes. In a particular aspect of the
invention, the polyethylene has an 12 with a lower limit of 0.1
g/10 minutes. All individual values and subranges from 0.1 g/10
minutes are included herein and disclosed herein. For example, the
polyethylene can have an I.sub.2 greater than or equal to 0.1, 0.2,
0.3, or 0.4 g/10 minutes.
[0089] Examples of polyethylenes having a density of 0.930 g/cc or
less, a melt index (I.sub.2) of 2.0 g/10 minutes or less, and a
peak melting point of 126.degree. C. or less that can be used in a
monolayer film according to some embodiments include those
commercially available from The Dow Chemical Company under the
names AFFINITY.TM., ELITE.TM. AT, and ATTANE.TM., such as
AFFINITY.TM. PL 1146G, AFFINITY.TM. 1888, ELITE.TM. AT 6401,
ELITE.TM. 5401G, and ATTANE.TM. 4203.
[0090] In the case of a monolayer film, other polyolefin resins can
be included in the monolayer in addition to the polyethylene for a
variety of reasons. For example, the monolayer can comprise
polyolefin resins, such as polypropylene and/or cyclic olefin
copolymers (e.g., cyclic olefin copolymers commercially available
from TOPAS Advanced Polymers such as TOPAS 6013), to provide
increased stiffness. In such embodiments, the additional polyolefin
resins can be provided in amounts less than 50 weight percent.
[0091] In embodiments where the monolayer comprises <100% of the
polyethylene described above, the monolayer further comprises one
or more additional polyethylene resins such as, for example, one or
more low density polyethylenes having a melt index from 0.1 to 5
g/10 minutes, one or more additional linear low density
polyethylenes having a density of 0.930 g/cc or less and a melt
index from 0.1 to 5 g/10 minutes.
[0092] It is preferred that the films used in embodiments of the
present invention be formed in a blown film or cast film process as
is generally known in the art, although other methods such as
lamination can be used.
[0093] The present invention provides a polyurethane-based coating
on an outer surface of the film. In the case of a multilayer film,
the outer surface is the outer surface of the second layer
comprising from 60 to 100 percent by weight polyethylene having a
density of 0.905 to 0.970 g/cm.sup.3 and a peak melting point in
the range of 100.degree. C. to 135.degree. C. In the case of a
monolayer film, the polyurethane-based coating is on one of the
outer surfaces of the film.
[0094] The term "polyurethane-based coating" is used to indicate
that upon curing, the coating comprises primarily polyurethane but
that the coating may also include, in some embodiments, unreacted
reactants (e.g., polyols, etc.) as well as other additives. In some
embodiments, the polyurethane is formed from (a) a polycarbamate
having an average of 2.5 or more carbamate functional groups and
(b) a polyaldehyde, wherein the polyaldehyde is a dialdehyde, a
trialdehyde, or an acetal or hemiacetal thereof, and wherein the
polyaldehyde comprises 2 to 20 carbon atoms. As set forth below,
other components, such as a triggering agent, can be used in the
mixture that forms the polyurethane.
[0095] As noted above, the polyurethane-based coatings used in
embodiments of the present invention are substantially free of
isocyanate groups, meaning that such coating having less than 5
mole percent (mol %) of --N.dbd.C.dbd.O groups (i.e., isocyanate
groups) based on total moles of carbamate groups plus isocyanate
groups in the composition, preferably, less than 3 mol %, or, more
preferably, less than 1 mol %, and, still more preferably, less
than 0.1 mol %. In some embodiments, the crosslinked polyurethane
coating cures at room temperature.
[0096] In some embodiments, a substantially isocyanate-free
multicomponent composition for forming the crosslinked polyurethane
comprises a polycarbamate as a first component and a polyaldehyde,
or an acetal or hemiacetal thereof, as a second component, wherein
the multicomponent composition further comprises an effective
amount of a triggering agent such that the first and second
components when combined form a composition that reacts to cure at
a temperature of from 0.degree. C. to less than 80.degree. C. to
form the crosslinked polyurethane, and, further wherein, the
composition resulting when all components of the multicomponent
composition are combined has a pH of 7.0 or less. The first
component and second component, when combined and cured form a
crosslinked polyurethane.
[0097] Preferably, in the first component, the polycarbamate has an
average of 2.5 or more, or, more preferably, 3.0 or more carbamate
functional groups, such as up to 100, or, preferably, up to 20
carbamate functional groups.
[0098] Preferably, the polycarbamate is, for example, the
condensation product of one or more polyols with an unsubstituted
carbamic acid alkyl ester or urea. Suitable polyols may include,
for example, an acrylic, saturated polyester, alkyd, polyether or
polycarbonate polyol. More preferably, the polycarbamate has
carbamate groups and hydroxyl groups in a ratio of the equivalents
of carbamate groups to the number of equivalents of hydroxyl
functional groups of from 1:1 to 20:1 or, preferably, 5.5:4.5 or
higher, or, preferably, up to 10:1. Such a ratio can be determined
by dividing the average number of carbamate functional groups by
the average number of hydroxyl functional groups in the
polycarbamate. The term "average number of hydroxyl functional
groups in the polycarbamate" is the average number of hydroxyl
groups left in the polycarbamate after it is made from a polyol and
means the number determined by hydroxyl titration of the
polycarbamate to determine its hydroxyl number, followed by
calculation of the number of hydroxyl groups reacted to form
carbamate groups in making the polycarbamate from a polyol by
comparing the hydroxyl number to the initial number of hydroxyl
groups in the polyol.
[0099] In the second component of the multicomponent composition
that forms the crosslinked polyurethane, the polyaldehyde, acetal
or hemiacetal thereof preferably has a solubility in water of from
0.015 to 0.20 gram of polyaldehyde per milliliter of water at
25.degree. C., preferably, up to 0.15 gram, or, preferably, 0.03
gram or more. Less preferred are more water soluble polyaldehydes,
such as glyoxal or glutaraldehyde.
[0100] Preferably, the polyaldehyde is chosen from a C.sub.5 to
C.sub.11 alicyclic or aromatic dialdehyde, or, more preferably, a
C.sub.6 to C.sub.10 alicyclic or aromatic dialdehyde, such as, for
example, (cis,trans)-1,4-cyclohexanedicarboxyaldehydes,
(cis,trans)-1,3-cyclohexanedicarboxyaldehydes and mixtures
thereof.
[0101] In the multicomponent composition, the triggering agent may
be an acid with a pKa of less than 6.0 in some embodiments.
[0102] The polycarbamate may have an average of 2.5 or more
carbamate groups, or an average of three or more carbamate groups,
or an average of four or more carbamate groups. As used herein, the
term "average number of carbamate groups" assumes full conversion
of the polyol or (poly)isocyanate used to form the polycarbamate
and means the total number average molecular weight of the
polycarbamate as determined by gel permeation chromatography
divided by the number of hydroxyl groups in the polyol used to make
the carbamate or the number of isocyanate groups in the
(poly)isocyanate used to make the carbamate, whichever is used. In
the case of an alkyd, the number of hydroxyl groups equals the
number average molecular weight of the alkyd as determined by GPC
divided by the hydroxyl equivalent weight of the alkyd, i.e. 56,100
mg KOH/mole KOH divided by the hydroxyl number in mg KOH/g resin.
Further, the number average molecular weight of the polycarbamate
can be determined by GPC of the polyol or polyisocyanate followed
by including in the added weight from reaction with urea or alkyl
carbamate to make the polycarbamate.
[0103] The polycarbamate can be acyclic, straight or branched;
cyclic and nonaromatic; cyclic and aromatic, or a combination
thereof. In some embodiments the polycarbamate comprises one or
more acyclic, straight or branched polycarbamates. For example, the
polycarbamate may consist essentially of one or more acyclic,
straight or branched polycarbamates.
[0104] Preferably the polycarbamate consists essentially of, and
more preferably consists of carbon, hydrogen, nitrogen, and oxygen
atoms. Still more preferably the polycarbamate consists of carbon,
hydrogen, nitrogen, and oxygen atoms, wherein each nitrogen and
oxygen atom is the nitrogen or oxygen atom of one of the two or
more carbamate groups of the polycarbamate.
[0105] Typically the polycarbamate is prepared by (a) reacting a
polyol with O-methyl carbamate or urea to give the polycarbamate;
(b) reacting a polyisocyanate with an
O-hydroxy(C.sub.2-C.sub.20)alkyl-carbamate to give the
polycarbamate; or (c) reacting the
O-hydroxy(C.sub.2-C.sub.20)alkyl-carbamate with methacrylic
anhydride to give a 2-carbamoylalkyl methacrylate, and then
polymerizing the 2-carbamoylalkyl methacrylate with an acrylic acid
monomer to give the polycarbamate as a polyacrylic-based
polycarbamate. The polycarbamates produced in (a) to (c) typically
will have different structures. Examples of these reactions are
illustrated graphically below in respective Schemes (a) to (c):
##STR00004##
wherein m is as defined for Scheme (a) and R(OH).sub.m, where m is
2 or greater.
##STR00005##
wherein m is an integer of from 2 or greater. Preferably m is an
integer of from 2 to 20. In some embodiments m is 2 or 3.
##STR00006##
wherein methacrylic anhydride is
[CH.sub.2.dbd.C(CH.sub.3)C(.dbd.O)].sub.2O and examples of acrylic
monomers are acrylic acid, (C.sub.1-C.sub.20)alkylacrylic acid
(e.g., the (C.sub.1)alkylacrylic acid is methacrylic acid), and
(C.sub.1-C.sub.20)alkyl acrylate (i.e., acrylic acid
(C.sub.1-C.sub.20)alkyl ester, e.g., (C.sub.1)alkyl acrylate means
methyl acrylate). Not shown in Scheme (c), other olefinic monomers
(e.g., styrene) can also be employed along with the acrylic
monomer, thereby preparing the polycarbamate as a poly(acrylic
other olefinic monomer)-based polycarbamate.
[0106] Preferably, each of the one or more acyclic, straight or
branched polycarbamates is prepared by reacting one or more polyols
with an unsubstituted carbamic acid alkyl ester or urea to yield
the one or more acyclic, straight or branched polycarbamates.
Suitable polyols may be (meth)acrylic polyols (i.e., a methacrylic
or acrylic polyol), polyalkylene polyols, polyether polyols (e.g.,
a poly(oxyalkylene) such as a poly(oxyethylene), such as a
poly(ethylene glycol), polyester polyols, or polycarbonate polyols.
Preferably, the polyalkylene polyol is a polyalkylene glycol.
Preferably the polyalkylene glycol is a polyethylene glycol or
polypropylene glycol.
[0107] More preferably, the polycarbamate comprises one or more
cyclic, nonaromatic polycarbamates and may consist essentially of
one or more cyclic, nonaromatic polycarbamates.
[0108] In some embodiments, each of the one or more cyclic,
nonaromatic polycarbamates is a N,N',N''-trisubstituted-cyanuric
acid derivative, wherein each substituent thereof independently is
of formula:
H.sub.2NC(.dbd.O)O--(CH.sub.2).sub.n--OC(.dbd.O)NH--CH.sub.2--((C.sub.3-C-
.sub.12)cycloalkyl)CH.sub.2--, wherein n is an integer of from 2 to
20. Preferably each n independently is an integer of from 2 to 12
and each cyclohexylene independently is a 1,3-cyclohexylene or
1,4-cyclohexylene. More preferably, n is 2 and the
N,N',N''-trisubstituted-cyanuric acid is the following
compound:
##STR00007##
[0109] The polycarbamate is substantially isocyanate free. The
presence or absence of molecules containing isocyanate groups can
be readily determined by Fourier Transform Infrared (FT-IR)
spectroscopy or carbon-13 nuclear magnetic resonance (.sup.13C-NMR)
spectroscopy.
[0110] Additional information regarding polycarbamates that can be
used to form the crosslinked polyurethane coating can be found in
U.S. Pat. No. 8,653,174, which is hereby incorporated by
reference.
[0111] With regard to the polyaldehyde that can be used to form the
crosslinked polyurethane coating, the polyaldehyde comprises one or
more cyclic, nonaromatic polyaldehydes or one or more aromatic
polyaldehydes. For example, the polyaldehyde comprises one or more
cyclic, nonaromatic polyaldehydes having from 3 to 20 ring carbon
atoms, and may consist essentially of one or more cyclic,
nonaromatic polyaldehydes having from 3 to 20 ring carbon
atoms.
[0112] More preferably, each cyclic, nonaromatic polyaldehyde
independently has from 5 to 12 ring carbon atoms, and, even more
preferably, is a mixture of
(cis,trans)-1,4-cyclohexanedicarboxyaldehydes and
(cis,trans)-1,3-cyclohexanedicarboxyaldehydes.
[0113] The polyaldehyde may comprise one or more acyclic, straight
or branched polyaldehyde having from 2 to 16 carbon atoms.
[0114] In another embodiment, each of the one or more acyclic,
straight or branched polyaldehydes having 16 carbon atoms or more
is prepared by hydroformylating a substantially water insoluble
multi-olefin-containing compound that is derived from a fatty acid
ester or, more preferably, a seed oil. For example, each of the one
or more acyclic, straight or branched polyaldehydes having 16
carbon atoms or more is prepared by hydroformylating a
multi-olefin-containing oligomer or polymer. Preferably, the
multi-olefin-containing compound that is derived from the seed oil
is a multi-olefin-containing fatty acid triglyceride having 48
carbon atoms or more.
[0115] Examples of suitable cyclic polyaldehydes are
trans-1,3-cyclohexanedicarboxaldehyde;
cis-1,3-cyclohexanedicarboxaldehyde;
trans-1,4-cyclohexanedicarboxaldehyde;
cis-1,4-cyclohexanedicarboxaldehyde; a mixture of
1,3-cyclohexanedicarboxaldehydes and
1,4-cyclohexanedicarboxaldehydes, preferably a 1-to-1 mixture
thereof; exo,exo-2,5-norbornanedicarboxaldehyde;
exo,exo-2,6-norbomanedicarboxaldehyde;
exo,endo-2,5-norbomanedicarboxaldehyde;
exo,endo-2,6-norbornanedicarboxaldehyde;
endo,endo-2,5-norbomanedicarboxaldehyde;
endo,endo-2,6-norbornanedicarboxaldehyde product (endo and exo
mixture); 3-(3-formylcyclohexyl)propanal;
3-(4-formylcyclohexyl)propanal; 2-(3-formylcyclohexyl)propanal;
2-(4-formylcyclohexyl)propanal; and
cyclododecane-1,4,8-tricarbaldehyde. The
trans-1,3-cyclohexanedicarboxaldehyde;
cis-1,3-cyclohexanedicarboxaldehyde;
trans-1,4-cyclohexanedicarboxaldehyde; and
cis-1,4-cyclohexanedicarboxaldehyde can be prepared by a process
comprising hydroformylating 3-cyclohexene-1-carboxaldehyde. The 1:1
mixture of 1,3- and 1,4-cyclohexanedicarboxaldehydes can be
prepared by a process comprising reacting acrolein and
1,3-butadiene in a Diels-Alder reaction to give
3-cyclohexenecarboxaldehyde (also called
1,2,3,6-tetrahydrobenzaldehyde), and hydroformylating the
3-cyclohexenecarboxaldehyde. The
exo,exo-2,5-norbomanedicarboxaldehyde;
exo,exo-2,6-norbornanedicarboxaldehyde;
exo,endo-2,5-norbomanedicarboxaldehyde;
exo,endo-2,6-norbornanedicarboxaldehyde;
endo,endo-2,5-norbomanedicarboxaldehyde; and
endo,endo-2,6-norbomanedicarboxaldehyde product (endo and exo
mixture) can be prepared by a process comprising reacting acrolein
and cyclopentadiene in a Diels-Alder reaction to give a
2-norbornene-5-carboxaldehyde, and hydroformylating the
2-norbomene-5-carboxaldehyde. The 3-(3-formylcyclohexyl)propanal;
3-(4-formylcyclohexyl)propanal; 2-(3-formylcyclohexyl)propanal; and
2-(4-formylcyclohexyl)propanal can be prepared by a process
comprising hydroformylating vinyl cyclohexene. The
cyclododecane-1,4,8-tricarbaldehyde can be prepared by a process
comprising trimerizing 1,3-butadiene to give
1,4,8-cyclododecatriene, and hydroformylating the
1,4,8-cyclododecatriene.
[0116] The polyaldehyde can be unblocked and unprotected or blocked
or protected. Blocked or protected polyaldehydes can be formed by
reacting an unblocked and unprotected polyaldehyde with a suitable
blocking or protecting group. Examples of protecting or blocking
groups for aldehyde groups are bisulfites (e.g., from reaction of
the polyaldehyde with sodium bisulfite), dioxolanes (e.g., from
reaction of the polyaldehyde with ethylene glycol), oximes (e.g.,
from reaction of the polyaldehyde with hydroxylamine), imines
(e.g., from reaction of the polyaldehyde with methylamine), and
oxazolidines (e.g., from reaction of the polyaldehyde with a
2-aminoethanol).
[0117] Preferred aldehyde protecting groups are, and preferred
protected polyaldehydes comprise, a hydrated group (>C(OH)2),
hemiacetal, acetal, or imine. These preferred protected
polyaldehydes can be prepared by respectively reacting the
polyaldehyde with water; one mole equivalent of an alkanol (e.g.,
methanol or ethanol); two mole equivalents of the alkanol; or
ammonia or a primary amine (e.g., methylamine). The hemiacetal,
acetal, or imine protecting group can, if desired, be removed by a
deprotection such as hydrolysis to give back the unprotected form
of the polyaldehyde. Such aldehyde protecting or blocking groups
and formation and removal (i.e., deprotection) is taught, for
example, in U.S. Pat. No. 6,177,514 B1.
[0118] Preferably, the polyaldehyde is stable in neat form (i.e.,
does not materially self-polymerize) and, more preferably, is
substantially water insoluble and is stable in neat form.
[0119] Additional information regarding polyaldehydes that can be
used to form the crosslinked polyurethane coating can be found in
U.S. Pat. No. 8,653,174, which is hereby incorporated by
reference.
[0120] The polycarbamates and polyaldehydes make up a
multicomponent composition that can be cured to form a crosslinked
polyurethane. In some embodiments, the multicomponent composition
may consist essentially of the polyaldehyde and the polycarbamate,
or separately, a triggering agent. In some embodiments, such
compositions may be curable at ambient temperature and consist
essentially of polycarbamate, polyaldehyde, and a triggering agent.
Such multicomponent compositions and ambient temperature curable
compositions are substantially formaldehyde free and substantially
isocyanate free in some embodiments.
[0121] The curing step preferably is initiated by a triggering
event, triggering agent, or a combination thereof. Such initiation
is performed by beginning exposure of the multicomponent
composition to the triggering event, triggering agent, or
combination thereof; and continuing such exposure for a period of
time sufficient to produce the crosslinked polyurethane coating. An
example of the triggering event is heat. Preferably heat is applied
radiantly although other means such as by convection or
combinations of means can be used. Preferably, the triggering agent
is used in an amount of from 0.001 wt % to 10 wt % of the
multicomponent composition, based on the total weight of solids in
the composition, more preferably from 0.01 wt % to 5 wt % thereof,
or, preferably from 0.1 wt % to 2 wt % thereof. Such amounts of the
triggering agent are referred to herein as "effective amounts" of
the triggering agent.
[0122] Any compound, substance or material suitable for increasing
a rate of reaction of a carbamate group (--O--C(.dbd.O)--NH.sub.2)
with an aldehyde group (--C(.dbd.O)H) can be employed as the
triggering agent. Examples of triggering agents are Lewis acids
(e.g., boron trifluoride etherate) and protic acids (i.e., Brcnsted
acids). Preferably, the triggering agent comprises a protic acid
characterizable as having a pK.sub.a of 6 or lower, wherein
pK.sub.a is negative base-10 logarithm of acid dissociation
constant, K.sub.a, of the protic acid. Thus, the ambient
temperature curable composition has a pH of 7.0, or less,
preferably, from pH 3 to pH<6. A preferred protic acid is an
inorganic protic acid or organic protic acid. A preferred inorganic
protic acid is phosphoric acid or sulfuric acid. A preferred
organic protic acid is carboxylic acid, phosphonic acid, or
sulfonic acid. A preferred carboxylic acid is acetic acid,
trifluoroacetic acid, propionic acid, or a dicarboxylic acid. A
preferred phosphonic acid is methylphosphonic acid. A preferred
sulfonic acid is methanesulfonic acid, benzenesulfonic acid, a
camphorsulfonic acid; para-toluenesulfonic acid, or
dodecylbenzenesulfonic acid. Examples of suitable Lewis acid curing
catalysts are AlCl.sub.3; benzyltriethylammonium chloride (TEBAC);
Cu(O.sub.3SCF.sub.3).sub.2; (CH.sub.3).sub.2BrS.sup.+Br.sup.-;
FeCl.sub.3 (e.g., FeCl.sub.3.6H.sub.2O); HBF.sub.4;
BF.sub.3.O(CH.sub.2CH.sub.3).sub.2; TiCl.sub.4; SnCl.sub.4;
CrCl.sub.2; NiCl.sub.2; and Pd(OC(O)CH.sub.3).sub.2.
[0123] The triggering agent can be unsupported (no solid support)
or supported, i.e. covalently bonded to a solid support. Examples
of supported triggering agents are supported curing catalysts such
as supported acid catalysts such as acid (H.sup.+) forms of cation
exchange-type polymer resins (e.g., ethanesulfonic acid,
241-[difluoro[(1,2,2-trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroe
thoxy]-1,1,2,2-tetrafluoro-, polymer with 1,1,2,2-tetrafluoroethene
sold under trade name NAFION NR 50 (E. I. du Pont de Nemours &
Co., Inc., Wilmington, Del.) and ethenylbenzenesulfonic acid
polymer with diethenylbenzene sold as AMBERLYS.TM. 15 (The Dow
Chemical Company, Midland, Mich., USA.).
[0124] To form the ambient temperature curable composition, a
polyaldehyde, an effective amount of a triggering agent and a
polycarbamate are mixed together.
[0125] The crosslinked polyurethane comprises a plurality of the
connecting carbamate diradicals. The term "connecting carbamate
diradical" refers to a molecule formed by reaction of an aldehyde
group of, or from the polyaldehyde and a carbamate group of, or
from the polycarbamate. The connecting carbamate diradical
comprises a hemi-aminal group or a geminal bis(urethane) group. The
hemi-aminal group comprises a diradical structure of formula
(I):
##STR00008##
The hemi-aminal group is formed from a reaction of one carbamate
group of the polycarbamate with one aldehyde group of the
polyaldehyde. The geminal bis(urethane) group comprises a moiety of
the formula (II):
##STR00009##
wherein R.sup.A is a residual of the polyaldehyde (e.g.,
dialdehyde) and R.sup.C is a residual of the polycarbamate (e.g.,
dicarbamate). The geminal bis(urethane) group is formed from a
reaction of two carbamate groups with one aldehyde group of the
polyaldehyde. Formation of the geminal bis(urethane) group from the
reaction of the polyaldehyde and polycarbamate occurs at acidic pH,
i.e., where pH of the ambient temperature curable composition is
pH.ltoreq.7.0, e.g., from pH 3 to pH<6; and that such formation
of the geminal bis(urethane) group cannot occur at basic pH, i.e.,
where pH of the invention ambient temperature curable composition
is pH >7.0, e.g., from pH 7.1 to pH 14). Typically one of the
two carbamate groups is from one polycarbamate molecule and the
other of the two carbamate groups is from another polycarbamate
molecule (i.e., each R.sup.C in formula (G-BU) is from a different
polycarbamate molecule). The type of connecting carbamate
diradicals in the crosslinked polyurethane can be readily
identified by analytical techniques such as, for example, one or
more of the following techniques: elemental analysis, infrared (IR)
spectroscopy (e.g., Fourier Transform IR spectroscopy or FT-IR
spectroscopy), mass spectrometry, and nuclear magnetic resonance
(NMR) spectroscopy (e.g., proton-NMR spectroscopy such as by
observing and integrating the proton on each of the carbon atoms
bearing the --OH in formula (H-A) and the proton on each of the
carbon atoms bearing R.sup.A in formula (G-BU)).
[0126] Preferably, the crosslinked polyurethane comprises at least
one geminal bis(urethane) group. More preferably, the crosslinked
polyurethane comprises a plurality of geminal bis(urethane)
groups.
[0127] Remarkably, the crosslinked polyurethane can be prepared
even when the polyaldehyde has only two aldehyde groups and the
polycarbamate has only two or more carbamate groups. This is
because at least one aldehyde group of the polyaldehyde is capable
of reacting with two carbamate groups, one from each of two
different adjacent polycarbamates, thereby crosslinking the
adjacent polycarbamates via the polyaldehyde so as to form one of
the aforementioned plurality of geminal bis(urethane) groups. Such
a double reaction produces a molecule of water as a byproduct.
[0128] The geminal bis(urethane) group allows even the dialdehyde
to react and crosslink the polycarbamate and thereby form the
invention crosslinked polyurethane having dialdehyde-derived
crosslinks. The geminal bis(urethane) group can also be formed with
the polyaldehyde having three or more aldehyde groups, which
polyaldehyde having three or more aldehyde groups thereby
crosslinks the polycarbamate so as to form the crosslinked
polyurethane having such polyaldehyde-derived crosslinks.
[0129] The multicomponent compositions used to form crosslinked
polyurethane coatings independently may further comprise one or
more additional ingredients. Examples of the additional ingredients
include an organic solvent, in the amount of 0.1 weight percent
(wt. %) to .ltoreq.90 wt. %, based on the total weight of solids in
the composition; a dehydrating agent, such as, for example,
carboxylic anhydrides, carboxylic acid halides (e.g., acetyl
chloride), and sulfonic acid halides (e.g., toluenesulfonyl
chloride) in the amount of 0.01 wt % to .ltoreq.10 wt. %, based on
the total weight of solids in the composition; as well as any of a
surfactant, a dispersing agent, a wetting agent, an adhesion
promoter, an ultraviolet (UV) light absorber, a light stabilizer,
one or more colorants or dyes, and an antioxidant.
[0130] Examples of suitable organic solvents are non-polar or polar
organic solvents such as, for example, an alkane (e.g., a
(C.sub.6-C.sub.12)alkane), ether (e.g., (C.sub.2-C.sub.12)ether,
e.g., a (C.sub.2-C.sub.12)dialkyl ether), carboxylic ester (e.g., a
(C.sub.2-C.sub.12)carboxylic ester), ketone (e.g., a
(C.sub.3-C.sub.12)ketone), secondary or tertiary carboxamide (e.g.,
a secondary or tertiary (C.sub.3-C.sub.12)carboxamide), sulfoxide
(e.g., a (C.sub.2-C.sub.12)sulfoxide), or a mixture of two or more
thereof.
[0131] Preferably, to reduce or eliminate the correlation between
pot life of a composition and coating drying time or coating
hardness, or both upon curing thereof, the multicomponent
compositions of the present invention comprise a curing inhibitor
such as, for example, water or a primary alkanol (e.g.,
(C.sub.1-C.sub.12)alkanols). The curing inhibitor may be used to
delay onset of or increasing length of time of curing or both of
the compositions until such time that curing is desirable, and can
be removed from the composition (e.g., by evaporation), thereby
initiating or increasing rate of curing thereof. Suitable curing
inhibitors have a boiling point at atmospheric pressure of at most
300.degree. C., more preferably at most 250.degree. C., and, still
more preferably at most 200.degree. C. Preferably, when the curing
inhibitor is present in the multicomponent compositions, it is
present in an amount of from 0.5 wt. % to 90 wt. % based on the
total weight of solids in the composition, or, more preferably, at
most 60 wt. %, and, still more preferably, at most 50 wt. %.
Preferably, the curing inhibitor concentration is at least 1 wt. %,
based on the total weight of solids in the composition, and, still
more preferably, at least 2 wt. %. The curing inhibitor can enable
the composition to maintain, if desired, a long pot life (e.g., 14
days or longer), and then, when curing is desired, can be removed
(e.g., by evaporation) so as to enable the curing and drying to
touch of the resulting composition in a comparable amount of time
as curing and drying to touch time of a same composition except
lacking the curing inhibitor and enabling the resulting cured and
dried coating thereof to exhibit a comparable degree of hardness as
a cured and dried coating prepared from the same composition except
lacking the curing inhibitor. Curing inhibitors may include, for
example, alkanols, water, or mixtures thereof, or, more preferably,
primary alkanols. Preferably, the alkanol is present at a
concentration of from 0.5 wt % to 50 wt %, based on the total
weight of solids in the composition, or more preferably, at most 20
wt %, and, still more preferably, at most 10 wt %. More preferably,
the alkanol concentration is at least 1 wt %, based on the total
weight of solids in the composition, and still more preferably at
least 2 wt %.
[0132] In some embodiments, the coating can comprise other
components such as oils and/or waxes. Examples of waxes that can be
used in coatings in some embodiments of the present invention
include, but are not limited to, paraffin wax, microcrystalline
wax, carnuba wax, polyfluoro wax, polyfluorochlor wax, and
combinations thereof. Examples of oils that can be used coatings in
some embodiments of the present invention include, but are not
limited to, corn oil, silicon oil, olive oil, canola oil,
sunflower, oil, and combinations thereof. While not wishing to be
bound by theory, the inclusion of minor amounts of oil and/or wax
is believed to modify the smoothness and gloss of films coated with
such coatings, to reduce or minimize tackiness of a coated film,
and/or to provide a desired kinetic coefficient of friction for the
intended use of the coated film. If desired, waxes and/or oils may
be added to the solution from suitable solvent media and mixed into
the coating to provide a homogeneous coating. The amount of waxes
and/or oils to use will depend on the inherent tackiness of the
coating (if any), the desired smoothness or gloss value, the type
of wax and/or oil to be used, and/or the desired kinetic
coefficient of friction for the final coated film.
[0133] The coating can be applied to the outer surface of the film
using a variety of techniques by which coatings are typically
applied to films including, for example, gravure coating, reverse
gravure coating, offset gravure coating, smooth roll coating,
curtain coating, spray coating, coating with a Mayer rod,
multi-roll coating, and flexographic coating, either as an overall
coating (100% coverage) and as a pattern applied coating (<100%
coverage). Persons of skill in the art with equipment to apply
solvent-based and/or water-based coatings and adhesives can readily
adapt their process to apply a polyurethane coating to a film to
obtain the coated films of the present invention.
[0134] The amount of coating applied to the film, in some
embodiments, can be at least 1 gram per square meter. As used
herein, the amount of coating is determined by measuring the
difference of the weight of the film before coating and after the
coating is applied and dried. In some embodiments, the amount of
coating applied to the film is up to 7 grams per square meter. The
amount of coating applied to the film, in some embodiments, is 1 to
7 grams per square meter. All individual values and subranges from
1 to 7 grams per square meter are included herein and disclosed
herein; for example, the amount of coating may be from a lower
limit of 1, 2, 3, 4, 5, or 6 grams per square meter to an upper
limit of 2, 3, 4, 5, 6, or 7 grams per square meter. For example,
the amount of coating can be from 3 to 5 grams per square meter in
some embodiments.
[0135] Various embodiments of coated films of the present invention
can have one or more desirable properties including, for example, a
broad thermal resistance range, high gloss, stable coefficient of
friction on the coated surface, and/or other properties. In some
embodiments, coated films of the present invention have a broad
thermal resistance range. Coated films, according to some
embodiments of the present invention, are thermally resistant when
subjected to a W-fold test at a temperature of at least 230.degree.
F. As used herein, the thermal resistance of a film using a "W-fold
test" is determined as follows. All references herein to "a W-fold
test" or "the W-fold test" refer to this procedure. The W-fold test
folds a coated film in a "W" shape such that there are uncoated
surface-to-uncoated surface and coated surface-to-coated surface
interfaces. The folded film is placed into a Sencorp Sealing
Machine set at 40 psi with a 2 second dwell time. The temperature
is varied from low to high in order to assess the temperatures at
which the uncoated surface-to-uncoated surface interface seals, but
the coated surface-to-coated surface interface does not seal. A
large temperature window between the temperature at which the
uncoated surfaces seal and a higher temperature at which the seal
between the coated surfaces fails is desired. The starting
temperature is set at 230.degree. F., held there for 2 seconds, and
then increased in 10.degree. F. until the coated surface-to-coated
surface interface starts to mar. The thermal resistance according
to the W-fold test is the highest temperature at which the coated
surface-to-coated surface interface does not mar.
[0136] In some embodiments, a coated film of the present invention
is thermally resistant when subjected to the W-fold test at a
temperature of at least 230.degree. F. A coated film of the present
invention is thermally resistant when subjected to the W-fold test
at a temperature of at least 240.degree. F. in some embodiments. A
coated film of the present invention, in some embodiments, is
thermally resistant when subjected to the W-fold test at a
temperature of at least 250.degree. F. A coated film of the present
invention, in some embodiments, is thermally resistant when
subjected to the W-fold test at a temperature of at least
260.degree. F. A coated film of the present invention is thermally
resistant when subjected to the W-fold test at a temperature of at
least 270.degree. F. in some embodiments, at least 280.degree. F.
in some embodiments, at least 290.degree. F. in some embodiments,
at least 300.degree. F. in some embodiments, at least 310.degree.
F. in some embodiments, at least 320.degree. F. in some
embodiments, at least 330.degree. F. in some embodiments, at least
340.degree. F. in some embodiments, at least 350.degree. F. in some
embodiments, at least 360.degree. F. in some embodiments, at least
370.degree. F. in some embodiments, at least 380.degree. F. in some
embodiments, at least 390.degree. F. in some embodiments. In some
embodiments, a coated film of the present invention is thermally
resistant when subjected to the W-fold test to a temperature up to
400.degree. F.
[0137] In some embodiments, coated films of the present invention
exhibit high gloss, particularly as compared to uncoated
polyethylene films. In some embodiments, coated films exhibit a
gloss of at least 70 units at 60.degree. when measured according to
ASTM D2457. Coated films, in some embodiments, exhibit a gloss of
up to 140 units at 60.degree. when measured according to ASTM
D2457. In some embodiments, coated films exhibit a gloss of 70 to
140 units at 60.degree. when measured according to ASTM D2457. All
individual values and subranges from 70 to 140 units at 60.degree.
are included herein and disclosed herein; for example, the gloss
can be from a lower limit of 70, 75, 80, 85, or units to an upper
limit of 90, 95, or 100 units. For example, in some embodiments,
the coated films can exhibit a gloss of at least 85 units at
60.degree. when measured according to ASTM D2457. In some
embodiments, coated films exhibit a gloss of 85 to 100 units at
60.degree. when measured according to ASTM D2457.
[0138] In some embodiments, coated films of the present invention
can exhibit a stable coefficient of friction on the coated surface.
For example, in some embodiments, the coated surface exhibits a
kinetic coefficient of friction of 0.10 to 1.5 when measured
film-to-metal according to ASTM 1894. The coated surface exhibits a
kinetic coefficient of friction of 0.10 to 0.40 when measured
film-to-metal according to ASTM 1894 in some embodiments.
[0139] Embodiments of the present invention also relate to articles
formed from any of the coated films disclosed herein. In some
embodiments, the article is a flexible package. In some
embodiments, the flexible package comprises a first coated film
according to the present invention and a second coated film
according to the present invention. Alternatively, the flexible
package can be formed from a single coated film of the present
invention that is folded.
[0140] In some embodiments, the flexible package is in the form of
one or more of the following: a pillow pouch, a sachet, and a stand
up pouch that is formed using techniques known to those of skill in
the art based on the disclosure herein.
[0141] The thickness of the coated film used to form the flexible
package can be selected depending on a number of factors including,
for example, the size of the flexible package, the volume of the
flexible package, the contents of the flexible package, the desired
properties of the flexible package, and other factors. In some such
embodiments, the coated film has a thickness used in a flexible
package of the present invention has a thickness of 20 to 200
microns. All individual values and subranges from 20 to 200 microns
are included herein and disclosed herein; for example, the
thickness of the coated film may be from a lower limit of 20, 30,
40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170,
180, or 190 microns to an upper limit of 30, 40, 50, 60, 70, 80,
90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200
microns.
[0142] Non-limiting examples of contents suitable for containment
by flexible packages of the present invention include comestibles
(beverages, soups, cheeses, cereals), liquids, shampoos, oils,
waxes, emollients, lotions, moisturizers, medicaments, pastes,
surfactants, gels, adhesives, suspensions, solutions, enzymes,
soaps, cosmetics, liniments, flowable particulates, and
combinations thereof.
[0143] Some embodiments of the invention will now be described in
detail in the following Examples.
EXAMPLES
Preparation of Reactant Compositions for Polyurethane Coating
[0144] The following Examples include a multilayer film coated with
a polyurethane coating according to an embodiment of the present
invention. The polyurethane coating used in these Examples is
prepared from two reactant compositions as follows.
Preparation of Solution for Coating
[0145] 29.0 grams of an acrylic polycarbamate (PARALOID.TM. EDGE
2121 resin commercially available from The Dow Chemical Company) is
placed into a speed-mixer cup. 30.8 grams of n-butyl acetate is
added and mixed for 1 minute at 1500 rpm. 2.0 grams of ethanol and
0.34 grams of a catalyst (K-CURE 1040 from King Industries, Inc.)
is added to the speed-mixer cup and mixed for 1 minute at 1500 rpm.
2.5 grams of a crosslinking agent, cyclohexanyl-dicarboxaldehyde,
is added and mixed a last time at 1500 rpm for 1 minute. The
crosslinking of the acrylic polycarbamate with the dialdehyde
results in a polyurethane with a urethane crosslink in the form of
an aminal. The resulting solution includes 35 weight percent solids
in butyl acetate. To reduce viscosity, the solution is further
diluted to 20-25 weight percent solids.
Preparation of Coated Film
[0146] The polyurethane coating is applied to a polyethylene film
as follows. The polyethylene film is a seven layer blown having an
A/B/B/B/B/B1/C construction as follows in Table 1:
TABLE-US-00001 TABLE 1 Peak Component(s) Nominal I.sub.2 Melting
(Nominal Density (g/10 Temp. Layer Thickness) (g/cm.sup.3) mins)
(.degree. C.) Top Layer DOWLEX .TM. 5075G (82%) 0.919 1.3 112 (A)
AGILITY .TM. 1021 (15%) 0.921 1.9 108 Slip Agent (1%) Anti-Block
(2%) (0.68 mils) Intermediate ELITE .TM. 5960 0.962 0.85 134 Layers
(B) (2.51 mils) Intermediate ELITE .TM. 5400 (85%) 0.961 1.0 118
Layer (B1) AGILITY .TM. 1021 (14%) 0.921 1.9 108 Slip Agent (1%)
(0.63 mils) Bottom AFFINITY .TM. 0.899 1.0 95 Layer PF 1146G (95%)
(sealing) Slip Agent (1%) (C) Anti-Block (4%) (0.68 mils)
[0147] The percentages in Table 1 are weight percentages based on
the total weight of the respective layer. Each of the polyethylene
resins are commercially available from The Dow Chemical Company.
The outer layer (A) is corona treated. 4-5 inch wide strips of the
polyethylene film are cut from the roll to be coated.
[0148] The polyurethane coating solution described above is mixed
immediately before application. The bubbles are allowed to
dissipate for 1 to 3 minutes. The film is attached to a glass plate
at the top only using double-sided tape with the corona-treated
side of the film facing upward. A paper towel is placed under the
glass plate to catch excess coating. A Mayer rod is placed at the
top of the film. The target coat weight of solids for these samples
is 3 g/m.sup.2 (gsm). Based on the percent solids, a Mayer rod is
selected and the resultant coat weight is measured using the
technique describe below. If the coat weight is too low, a higher
number Mayer rod is selected and so forth. Most of the samples in
this Example are prepared using a #4 Mayer bar for 31 weight
percent solids coating solutions and a #6 Mayer bar for 29 weight
percent solids coating solutions.
[0149] 1 to 1.5 milliliters of the coating solution is added to the
top of the film below the Mayer rod. The Mayer rod is pulled down
quickly to coat the corona treated side of the film. The coating is
performed in a hood immediately adjacent to a drying oven. The wet
coating is placed into a 70-75.degree. C. vacuum oven for 3 minutes
using a dry-ice cooled trap to capture the solvent. A slight vacuum
of .about.-5 inches Hg is pulled while leaving the needle valve
open as full vacuum is not desirable. After 3 minutes, the film is
removed placed on a wire rack to cool. Once cool, the film is
transferred to a metal plate, and the edges secured with magnets to
prevent excessive curl. The films are allowed to cure for 7 days
under ambient conditions before further testing.
Coat Weight
[0150] The amount of coating on the film is measured as follows. A
sheet of aluminum foil is attached to a glass plate with double
sided tape and smoothed down as much as possible. A Mayer rod is
placed at the top of the foil. 1 to 1.5 milliliters of the
polyurethane coating solution is applied to the top portion of the
aluminum foil below the Mayer rod. The Mayer rod is used to draw
down the coating solution, and the plate/foil were placed into a
70-75.degree. C. vacuum oven at .about.-5 in Hg for one minute. The
timing is important because at 1 minute most of the solvent is
removed when non-absorbent aluminum foil is the substrate, but at
longer times the coating is too cross-linked to be easily removed.
A 9.70 cm.times.9.70 cm square template is placed over the coated
aluminum foil, and then a curved teasing needle is used to indent
the aluminum foil around the template. Metal handled scissors are
used to cut along the indented lines to free a piece of coated
aluminum foil in the shape of the template. The coated foil is
weighed on a four place analytical balance to obtain a first
measurement (W1). Ethyl acetate or methyl ethyl ketone are used to
wash the coating off of the foil. The washed aluminum foil is dried
to remove residual solvent. The aluminum foil is then weighed again
to obtain a second measurement (W2). A coat weight is calculated
using the following formula:
coat weight = K .times. ( W 1 - W 2 ) A ##EQU00001##
where K=1.times.10.sup.6 mm.sup.2/m.sup.2 and A is the area of the
substrate in mm.sup.2. With the 9.70 cm.times.9.70 cm square
template, the area (A) is 9409 mm.sup.2.
Example 1
[0151] A coated film of the present invention is evaluated for heat
resistance testing. A coated film is prepared as described above
with a coat weight of .about.3 g/m.sup.2. The heat resistance of
the coated film is compared to an uncoated polyethylene film having
the same construction as above without the coating.
[0152] First, the films are screened for potential heat resistance
as follows. A TISH-200 impulse sealer (model E82163(s)) is used for
the heat resistance screening with the dial set to "9", the maximum
value. Under this condition, an uncoated polyethylene film would
melt right through, resulting in two pieces of film on either side
of the heating bar. A coated film of the present invention (as
described above) that has cured for a minimum of 7 days is cut into
1-inch strips perpendicular to the draw-down direction. Typically,
the strips are taken from the middle section of the film, away from
the very top or bottom. The film strip is looped over onto itself
so that the coated surface is on the outside of the loop and the
uncoated surface is on the inside of the loop. The loop is placed
into the heat zone of the sealer, and the lever is firmly pressed
down. The heat automatically stops after 3 seconds. The lever is
released and the loop is removed from the heat zone. Scores are
assigned according to the quality of the heat seal. A score of "0"
is assigned if the strip melts completely through and the loop is
cut off. A score of "5" is assigned if the loop sealed and stuck
together, but the seal line is very soft when removed. A score of
"10" is assigned if the loop is sealed and stays together and the
seal appears strong. In this evaluation, only scores of 0 and 5 are
obtained which essentially reduced the testing to "pass" or "fail".
Each film is tested four times and the overall score was an average
of the four trials. The uncoated films failed this heat resistance
screening test, while the coated films of the present invention
passed by forming seals.
[0153] Samples that passed the initial heat resistance screening
are further evaluated for heat resistance using the W-fold test.
The coated film of the present invention (Inventive Film 1) started
to mar at a temperature of 270.degree. F. As uncoated polyethylene
mars or even starts to seal at 230.degree. F., the coated film
shows an improvement in heat resistance.
Example 2
[0154] The gloss values of coated films according to embodiments of
the present invention (Inventive Films 1-3) are compared to the
gloss values of an uncoated film (Comparative Film A) and a
comparative coated film (Comparative Film B). The coated film
according an embodiment of the present invention (Inventive Film 1)
is prepared using the coating as described above.
Preparation of Coating for Inventive Film 2
[0155] 5.8 grams of the acrylic polycarbamate (described above) is
placed into a glass vial. 16.59 grams of ethyl acetate is added to
the vial and is shaken by hand until thoroughly mixed. 0.04 grams
of wax (Synaceti 125 commercially available from Werner G. Smith,
Inc.) and 0.04 grams of corn oil are added to the vial. The vial is
placed in a 73.degree. C. oven for 1 minute, is removed from the
oven, and then shaken by hand to visually evaluate solubility. This
process is repeated until the wax and oil are fully dissolved. 0.4
grams of ethanol and 0.068 grams of a catalyst (K-CURE 1040 from
King Industries, Inc.) are added to the vial and is shaken by hand
until thoroughly mixed. 0.5 grams of a crosslinking agent,
cyclohexanyl-dicarboxaldehyde, is added to the vial and the vial is
shaken a final time by hand until mixed thoroughly.
Preparation of Coating for Inventive Film 3
[0156] 5.8 grams of the acrylic polycarbamate (described above) is
placed into a glass vial. 16.59 grams of a 50/50 by weight mixture
of ethyl acetate and cyclohexane is added to the vial and is shaken
by hand until thoroughly mixed. 0.04 grams of wax (Synaceti 125
commercially available from Werner G. Smith, Inc.) and 0.04 grams
corn oil are added to the vial. The vial is placed in a 73.degree.
C. oven for 1 minute, is removed from the oven, and then shaken by
hand to visually evaluate solubility. This process is repeated
until the wax and oil are fully dissolved. 0.4 grams of ethanol and
0.068 grams of a catalyst (K-CURE 1040 from King Industries, Inc.)
are added to the vial and is shaken by hand until thoroughly mixed.
0.5 grams of a crosslinking agent, cyclohexanyl-dicarboxaldehyde,
is added to the vial and the vial is shaken a final time by hand
until mixed thoroughly.
[0157] A coated film according one embodiment of the present
invention (Inventive Film 2) is prepared as described above, except
that the Coating for Inventive Film 2 is applied to the film. A
coated film according to another embodiment of the present
invention (Inventive Film 3) is prepared as described above, except
that the Coating for Inventive Film 3 is applied to the film.
[0158] Comparative Film A is the base film as described above.
Comparative Film B includes the same base film with a polyurethane
coating that includes isocyanates. The coating in Comparative Film
B is applied at 31% solids, coated at 3 grams/m.sup.2, and allowed
to cure for at least 7 days at ambient temperature.
[0159] The gloss test performed is ASTM D2457 using a BYK Gardner
Micro-Tri-Gloss Gloss Meter. The Meter is set to record both
20.degree. and 60.degree. gloss for each sample, measured from top
to bottom in 8 different locations while avoiding the very top and
very bottom of the film. The gloss varies due to imperfections in
both the coating and in the underlying polyethylene film.
Therefore, average and standard deviation are measured for each
film sample at 20.degree. and 60.degree.. Two samples of each film
are measured (except for Inventive Film 2), and the results are
shown in Table 2:
TABLE-US-00002 TABLE 2 Sample Avg. Std. Dev. Avg. Std. Dev. No.
20.degree. Gloss 20.degree. Gloss 60.degree. Gloss 60.degree. Gloss
Comparative 1 66.8 16.0 101.1 3.0 Film A 2 71.4 5.5 100.6 1.2
Comparative 1 67.5 27.5 97.8 15.1 Film B 2 100.0 7.3 116.1 1.5
Inventive 1 84.9 13.4 108.8 1.2 Film 1 2 92.4 9.6 109.3 1.3
Inventive 1 89.9 25.8 108.5 17.0 Film 2 Inventive 1 82.8 24.0 117.1
32.5 Film 3 2 79.7 24.4 108.2 17.0
The 60.degree. gloss of the Inventive Films is comparable to
Comparative Film B (polyurethane coating with isocyanates), and
improved over Comparative Film A (uncoated). The 20.degree. gloss
also compares favorably.
* * * * *